1. Field of the Invention
The invention relates to a method for producing a permanent mechanical and electrical connection between a stranded wire and a connecting element. One end of the stranded wire is thereby welded to the connecting element. The invention also relates to a connection between a connecting element and a stranded wire produced using the method according to the invention
2. Description of Related Art
A stranded wire or strand is a conductor consisting of a plurality of thin individual wires. The individual wires can be jointly surrounded coaxially by an insulating sheath and possibly additionally by a common outer conductor. Several such stranded wires can run next to one another in a cable.
Stranded wires have in common the advantage of particularly high flexibility and an only slight susceptibility to conductor breaks, even under mechanical stresses such as vibrations or shearing and bending forces acting on the stranded wire.
In order to connect the stranded wire with a connecting element such as a plug connector or a terminal it is known to provide a stripped end of the stranded wire with a ferrule which holds the individual wires of the strand firmly together and prevents damage to the individual wires being caused by a clamping screw or similar. The ferrule can for example be crimped together with the end of the stranded wire. As an alternative it is known for the strand to be soldered to a connecting element.
However, stranded wires or strands which are for example used for the transmission of high currents in automobiles generally have a large conductor cross section and a large number of individual wires, as a result of which the connection of the strand with the connecting element is made even more difficult. Moreover, the connection points are regularly subjected to high external forces such as vibrations, so that a particularly stable and durable fixing of the stranded wire to the connecting element is necessary.
At present, stranded wires with a large cross section or with a large number of individual wires are regularly welded to the connecting element, since a permanent substance-to-substance bond can be created quickly and comparatively economically by means of welding. For this purpose, the strand is laid on a flat contact surface of the connecting element, pressed flat in such a way that as many individual wires of the strand as possible are in direct contact with the contact surface, and the individual wires are then welded together with the contact surface. However, it has been found that such welded connections cannot be created with consistent resilience and durability due to the individual wires in some cases not being oriented in an ordered manner during welding, so that welded connections cannot always durably withstand the vibrations to which the connection point can be exposed.
It is known from EP 2 362 491 A1, U.S. Pat. No. 3,717,842 and DE 10 2013 105 669 A1 for a permanent mechanical and electrical connection between a stranded wire and a connecting element to be produced in that one end of the stranded wire is welded to the connecting element, whereby the end of the stranded wire is inserted in a crimping recess prior to welding and the connecting element is crimped together with the stranded wire.